Method and apparatus of a mobile communication system which reduces power consumption by observing only the starting slot on a TDMA radio channel

• US 6,819,661 B2
• Filed: 06/10/1997
• Issued: 11/16/2004
• Est. Priority Date: 03/15/1996
• Status: Expired due to Term

• Current Assignee: NTT Mobile Communications Network Inc. (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Murase, Atsushi, Kobayashi, Katsumi, Okajima, Ichiro, Takami, Tadao, Maebara, Akihiro
• Primary Examiner(s): Yao, Kwang Bin
• Assistant Examiner(s): George, Keith M.
• Application Number:
  US08/860,240
• Publication Number:
  US 20020044543A1
• Time in Patent Office: 2,716 Days
• Field of Search: 370/337, 370/336, 370/329, 370/347, 370/342, 370/343, 370/458, 370/468, 370/348, 370/349, 370/311, 370/437
• US Class Current: 370/347
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 74/04 Scheduled access hybrid access H04W74/02
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Base station generates a mobile station identifier which indicates a mobile station that a data signal is addressed thereto, and a head slot having a data signal when there is a data signal that has a length to be able to transmitted using one slot of a TDMA radio channel. When there is a data signal that has a length to be not able to transmitted using one slot, base station generates a head slot and continuous slots which contain at least a part of data signal. Base station transmits the head slot by using the starting slot which located at predetermined position every mobile station on the TDMA radio channel, and transmits the continuous slots by using slots which follow the starting slot. Mobile station receives the starting slot, and stops reception if the starting slot is not the head slot. If the starting slot is the head slot, the mobile station judges the mobile station identifier. Furthermore, if the mobile station identifier indicates other mobile station, the mobile station stops reception, on the other hand, if the mobile station identifier indicates itself, the mobile station receives the continuous slot.

Claims

1. A method for transmitting data signals to one or more mobile stations through a TDMA radio channel which is divided into recurring rounds of slots, the method comprising the steps of:

(a) defining in every round at least one starting slot for a mobile station, each starting slot being located at the same slot position in each round;

(b) transmitting slot assignment information to the mobile station, using a common starting slot assigned commonly to a group of mobile stations including the mobile station, in order to notify the defined at least one starting slot to the mobile station; and

(c) transmitting a data signal of a variable length to the mobile station, using one or more physically consecutive slots beginning with one of the defined at least one starting slot,

wherein the mobile station only monitors, in each round, the defined at least one starting slot and the common starting slot and, when any one of the defined at least one starting slot carries a data signal addressed to it, receives the data signal from one or more physically consecutive slots beginning with the one of the at least one starting slot.

2. A method according to claim 1, wherein each slot carries information indicating a slot type thereof and a number of subsequent slots necessary to transmit any portion of a signal that remains to be transmitted, and whether or not it carries a part or the whole of the signal.

3. A method according to claim 2, wherein one type of slots is signal slots, which carry a data signal, and another type of slots is vacant slots, which do not carry a data signal.

4. A method according to claim 1, wherein an interval between two neighboring starting slots is changed according to a volume of communication traffic.

5. A method according to claim 1, further comprising the step of transmitting a synchronous word, using a slot, wherein the mobile station, at the beginning of a communication, checks every slot in a round to detect a position of the slot that contains the synchronous word and recognize the slot as its starting slot.

6. A method according to claim 1, further comprising the step of transmitting a second set of data signal of a variable length to the mobile station, using one or more physically consecutive slots immediately succeeding one or more physically consecutive slots used to transmit a first set of data signal of a variable length to the same mobile station, wherein the mobile station, after receiving the first set of data signal, checks a slot immediately succeeding the one or more physically consecutive slots for transmission of the first set of data signal to determine if there is any data signal addressed to the mobile station.

7. A method according to claim 1, further comprising the step of reassigning a new starting slot to the mobile station.

8. A method according to claim 1, wherein an interval between two neighboring starting slots is changed according to a time delay in transmission of data signals that occurs after the data signals are generated.

9. A network that transmits data signals to one or more mobile stations through a TDMA radio channel which is divided into recurring rounds of slots, the network comprising:

(a) a slot assigner that defines in every round at least one starting slot for a mobile station, each starting slot being located at the same slot position in each round;

(b) a slot assignment information transmitter that transmits slot assignment information to the mobile station, using a common starting slot assigned commonly to a group of mobile stations including the mobile station, in order to notify the defined at least one starting slot to the mobile station; and

(c) a data signal transmitter that transmits a data signal of a variable length to the mobile station, using one or more physically consecutive slots beginning with one of the defined at least one starting slot,

wherein the mobile station only monitors, in each round, the defined at least one starting slot and the common starting slot and, when any one of the defined at least one starting slot carries a data signal addressed to it, receives the data signal from one or more physically consecutive slots beginning with the one of the defined at least one starting slot.

10. A network according to claim 9, wherein each slot carries information indicating a slot type thereof and a number of subsequent slots necessary to transmit any portion of a signal that remains to be transmitted, and whether or not it carries a part or the whole of the signal.

11. A network according to claim 10, wherein one type of slots is signal slots, which carry a data signal, and another type of slots is vacant slots, which do not carry a data signal.

12. A network according to claim 9, wherein the transmitter transmits a second set of data signal of a variable length to the mobile station, using one or more physically consecutive slots immediately succeeding one or more physically consecutive slots used to transmit a first set of data signal of a variable length to the same mobile station, and the mobile station, after receiving the first set of data signal, checks a slot immediately succeeding the one or more physically consecutive slots for transmission of the first set of data signal to determine if there is any data signal addressed to the mobile station.

13. A network according to claim 9, wherein the slot assigner changes an interval between two neighboring starting slots according to a volume of communication traffic.

14. A network according to claim 9, further comprising the step of transmitting a synchronous word, using a slot, wherein the mobile station, at the beginning of communication, checks every slot in a round to detect a position of the slot that contains the synchronous word and recognize the slot as its starting slot.

15. A network according to claim 9, wherein the slot assigner reassigns a new starting slot to the mobile station.

16. A network according to claim 9, wherein the slot assigner changes an interval between two neighboring starting slots according to a time delay in transmission of data signals that occurs after the data signals are generated.

17. A method of receiving a data signal of a variable length by a mobile station through a TDMA channel which is divided into recurring rounds of slots, wherein at least one starting slot is defined for the mobile station at the same slot position in each round, the method comprising the steps of:

(a) receiving at the mobile station, using a common starting slot assigned commonly to a group of mobile stations including the mobile station, slot assignment information notifying the mobile station of the at least one starting slot defined for the mobile station;

(b) only monitoring at the mobile station, the defined at least one starting slot and the common starting slot in each round to determine if any one of the defined at least one starting slot and the common starting slot carries a data signal addressed to the mobile station; and

(c) if any one of the defined at least one starting slot carries a data signal addressed to the mobile station, receiving at the mobile station the data signal of a variable length from one or more physically consecutive slots beginning with the one of the defined at least one starting slot.

18. A method according to claim 17, further comprising the step of putting the mobile station in a power saving mode and temporarily waking up the mobile station from the power saving mode when there comes the defined at least one starting slot assigned and the common starting slot to the mobile station.

19. A method according to claim 17, wherein after having received a data signal of a variable length contained in one or more physically consecutive slots, the mobile station monitors a slot immediately succeeding the one or more physically consecutive slots to receive any subsequent data signal addressed to the mobile station.

20. A method according to claim 17, wherein the mobile station, at the beginning of communication, monitors every slot in a round to detect a position of slot in which a synchronous word is present.

21. A method according to claim 17, wherein

when waiting to receive a data signal, the mobile station can switch between a first mode where it only monitors the defined at least one starting slot and the common starting slot in each round and a second mode where it monitors every slot in each round, and

a data signal of variable length is transmitted to the mobile station, using one or more physically consecutive slots beginning with one of the defined at least one starting slot if the mobile station operates under the first mode, or using one or more physically consecutive slots beginning with an arbitrary selected slot if the mobile station operates under said second mode.

22. A mobile station that receives a data signal of a variable length through a TDMA channel which is divided into recurring rounds of slots, wherein at least one starting slot is defined for the mobile station at the same slot position in every round, the mobile station comprising:

(a) a receiver that receives, using a common starting slot assigned commonly to a group of mobile stations including the mobile station, slot assignment information notifying the mobile station of the defined at least one starting slot and, if any one of the defined at least one starting slot carries a data signal addressed to the mobile station, receives the data signal of a variable length from one or more physically consecutive slots beginning with the one of the defined at least one starting slot; and

(b) a control apparatus that only monitors the defined at least one starting slot and the common starting slot in each round to determine if any of the defined at least one starting slot and the common starting slot carries a data signal addressed to the mobile station.

23. A mobile station according to claim 22, further comprising a power consumption controller that puts the mobile station in a power saving mode and temporarily wakes up the mobile station from the, power saving mode when there come the defined at least one starting slot and the common starting slot to the mobile station.

24. A mobile station according to claim 22, wherein after having received a data signal of a variable length contained in one or more physically consecutive slots, the mobile station monitors a slot immediately succeeding the one or more physically consecutive slots to receive any subsequent data signal addressed to the mobile station.

25. A mobile station according to claim 22, wherein the mobile station, at the beginning of communication, monitors every slot in a round to detect a position of a slot in which a synchronous word is present.

26. A mobile station according to claim 22, wherein

when waiting to receive a data signal, the mobile station can switch between a first mode where it only monitors the defined at least one starting slot and the common starting slot in each round and a second mode where it monitors every slot in each round, and

a data signal of variable length is transmitted to the mobile station, using one or more physically consecutive slots beginning with the defined at least one starting slot if the mobile station operates under the first mode, or using one or more physically consecutive slots beginning with an arbitrary selected slot if the mobile station operates under said second mode.